The Manley Reference Compact 160 Watt Monoblocks were built at the old VTL factory back before the Manley/VTL split-up in 1993. They put out somewhere between 120 and 160 watts depending on which output tubes were in there and where you declared maximum to live, at 1.5% or 3% THD at 1KHz.

The earliest units were called Manley Reference Compact 150's.

They were 4-output tube designs usually strapped in Ultra-Linear operating mode, although some might have had triode-tetrode switches on the faceplate (triode was always "up"). The 160's used the GE6550 output tubes before 1990 and the KT90's after that. The pre-1990 units were called Reference Compact 150's. The Input tube was always the 12AT7A or 6201. Some early models might have used the 12BH7A for driver tube although most of the actual production models probably used 6350 driver tubes. (Sorry my memory is failing me. Just read the number printed on the tube as the two types are not interchangeable without circuit board modification.) Those two tube types have the grids and cathodes swapped on the pinout so make a big note that the 6350 and the 12BH7A are NOT interchangeable without reworking the circuit board!


Manley 160's had a sheet-metal "Compact"chassis and stainless-steel covers. Bias readout tipjacks are located behind the faceplate on the top deck while the bias adjustment pots are located in near each output tube on the top deck. Additionally there are two driver balance measurement points and corresponding trimpot to set the AC balance located near the driver tube. These 160's were quite similar to the VTL Compact 100's of the time. Both the output and power transformers were manufactured by Mercury Magnetics. The output tranny was factory set for an optimal 5 Ohm speaker load. The serial badge will look something like this.


If it doesn't say "MAN150C###" or "MAN160###" then you don't have a Manley Reference Compact 150 or 160. You can also see the standard 5-way binding posts here. These amplifiers were probably built before 1989 when the blue negative binding posts were phased out and replaced with black ones. Later Manley 160's had the silver plated binding posts.

This particular amplifier had an XLR connector and volume control fitted. Not all of them did. The XLR was paralleled to the RCA and was always unbalanced as the input circuit is unbalanced in this model. I cannot recall any balancing transformers being fitted to these.

The power cord was captive, so you can't use your tweaky audiophile power cords with these unless you go hack 'em.

This model ceased production in 1993 and was never manufactured at the new Manley Labs factory. Although a similar amplifier in the "L-Box chassis" was built here at the Manley Labs factory: The Manley Lab Series 100w mono. 


Here's a top-down view of the old Manley 160.


For biasing info, read the owner's manual.

Additional notes for biasing: you READ the bias on these amps via the four black tip jacks located in a row along the front of the top deck just behind the faceplate, and yes, that is the MAINS fuse there in the left corner of the top deck. Your positive meter lead goes in each of these tip jacks while your negative meter lead is anchored to the negative binding post or some other good round. You SET the bias (for a 0.275 to 0.300mV reading) by adjusting each of the bias trim pots located in a row behind the output tubes. The other blue pot near there, next to tube #3 is the MASTER BIAS so turning that pot will raise or lower the bias on all four output tubes at once.

The blue trim pot that is located just behind and between the driver and input tubes, in front of the driver and input filter caps, is the AC BALANCE ADJUST. There are two tip jacks located to the right of output tube #4 that you put your meter in and read the AC voltage there. The quick and easy way to adjust this is to just leave it alone as it will be "close enough". The more advanced thing to do is to play a sine wave through your amps and through your speakers (or dummy load, don't ever run tube amps into NO load) and null out the voltage found there. The best way to adjust this is to use distortion analyzers and oscilloscopes and trim for lowest THD like we do.

If all the tubes read zero bias, then you either forgot to turn the amplifier on, or your B+ fuse has blown. Not all of the 160's had B+ fuses. But if it does, the B+ fuse will be located on the rear of the amplifier, (the fuseholder that you use a flat screwdriver to open) and he should be a 4/10ths Amp SLO-BLO fuse, preferably a ceramic-bodied type MDA series. (The glass ones tend to blow in a way that destroys the fuseholder.) When you replace that fuse, keep an eye on the output tubes because one of them is probably bung, ran away, and caused the fuse to blow.

The MAINS fuse is the one on the top deck all the way to the left-front, and if he blows, then you probably have a major problem.

We still do service these old MANLEY amps, so if you need help with yours, please first read the owner's manual, and then if you still have questions, you can fill out our Tech Support Form. If you have a VTL-branded amplifier feel free to use the info on this page if it will help you, but please don't bother us about servicing or answering questions about it as it is not our product and we do not service VTL gear at MANLEY LABS. Just MANLEY-branded stuff.




  • Driver 12BH7A or 6350
  • Input l x 12AT7WA
  • Input sensitivity: 0.750V 
  • Input Impedance: 100 kOhm
  • ALL-TUBE monoblock design
  • Output load impedance: Factory set for 5 Ohms nominal
  • Max output power: 160 watts on a good day
  • S/N ratio: better than -90 dB
  • Power consumption: yes, definitely
  • RCA Unbalanced input (sometimes had paralleled XLR connector)
  • Large filter / reservoir capacitors
  • Top deck bias measurement and adjust
  • Mercury Magnetics power & output transformers
  • Factory set for 100V, 120V or 220-240VAC operation for original destination country's mains voltage.
  • Operating Mains Voltage changeable with power transformer re-wiring and fuse value change.
  • Mains Voltage Frequency: 
  • Dimensions: slightly bigger than a bread box
  • Shipping weight: around 40 lbs. (Sorry, I haven't picked one up in awhile. They do not come in for service very often.)

Specifications subject to change because they just might.